<ion-select placeholder="选择一个年级" [(ngModel)]="value" (ionChange)="handleChange($event)">
    <div slot="label">
        年级
        <ion-text color="danger" *ngIf="required">*</ion-text>
    </div>
    <ion-select-option value="1">一年级</ion-select-option>
    <ion-select-option value="2">二年级</ion-select-option>
    <ion-select-option value="3">三年级</ion-select-option>
    <ion-select-option value="4">四年级</ion-select-option>
    <ion-select-option value="5">五年级</ion-select-option>
    <ion-select-option value="6">六年级</ion-select-option>
    <ion-select-option value="7">初一</ion-select-option>
    <ion-select-option value="8">初二</ion-select-option>
    <ion-select-option value="9">初三</ion-select-option>
    <ion-select-option value="10">高一</ion-select-option>
    <ion-select-option value="11">高二</ion-select-option>
    <ion-select-option value="12">高三</ion-select-option>
</ion-select>